Electric heater.



L. HELLEF.

ELECTRIC HEATER.

APPLICATION FILED 05.1.10. 1915.

1 ,216,31 3. Patented Feb. 20; 1917.

WIIAIIIIIIIIIJIIIIIIII'IIL LEO HELLER, OF TEPLITZ; AUSTRIA- HUN GARY.

ELECTRIC HEATER.

Specmcatioii 01' Letters Patent.

Patented Feb. 20, 1917.

Application filed December 10, 1915. Serial No. 66,163.

To all who-m it may concern:

lie it known that I, Leo HELLER, a citizen of the Austrol'lungarian Empire, and residing at Teplitz, Bohemia, Austria-Hungal-y, have invented a certain new anduse ful Improved Electric Heater, of which the following is a specification.

'llhisinvention relates to an electric heating device for cooking utensils, particularly those made of earthenware, glass, china, metal china and the like.

It is already known to bring about the electric heating of cooking utensils and the like by the aid of electric heaters, the resistances of which are embedded in a suitable insulating substance such as cement, sand, powdered quartz, ceramic putty .orthe like. The employment of heaters. of this kind however is accompanied with more or'less difliculty because a. sufliciently close contact between the "essel to be heated and the heater can only be secured by the employment of'special means, such as screws or the like. i

The object of the present invention is'to obviate all these deficiencies in an absolutel reliable way without special mechanical aid: and in such a manner that close contact between the vessel and the heater is as'suredi The invention consists in embedding the. heater proper in a plate shaped metal or porcelain dish which is filled with an insir lating substance in a plastic condition, the said substance consisting of 70% of pure ceramic clay, 20% of white pulverized rave-l, 5% of crushed mica,

reschen sand and which is inserted into a hollow space provided'in the bottom of the vessel to be heated in. such a way, that the insulating mass, which becomes completely hardened by heating through the wires, adapts itself accurately to surface of the vessel.

This vessel of porcelain or earthenware isprovided with a conductive coating, which the under enables specially quick heating by the heater n question to be. obtained and is characterized bythe fact, that on the bottom of the vessel :1 "metal ring entirely uniform with the metal coating is arranged, being'at-a tached to the vessel by providing thesamef' with a thin conductive deposit. The metal ring is then soldered or weldedon to this thin deposit and then finally both and the ring are coated together with thicker conductive deposit. Vesselsof such the vessel and 5% of.

resistance Fig. 4 is a like section through a similar vessel but harting a conductive coatingl,

Fig. 5 is a section through the right bottom corner 01 the vessel shown on Fig. 4 on an enlarged-scale.

Referring to the'drawing '1: denotes the resistance wires secured to the contacts 6, 80

the said wires being suitably arranged in spirals in one or more planes, and embedded in an insulating mass which consists of 70% of pure ceramic modeling clay, 20% of white'pulv erized gravel, of mice and 5%of Preschen sand. This compound has the advantage that the heater can stand day and night unc er current, Without intermission 'vvithout burnin out, while the heaters hitherto known inevitably burn out 90 if one forgets toturn off the current aftercompletion of the heating process.

.In addition the heater possesses the further advantage, that the contents of the ves-' selcontinueto boil for to QOniinutes after the current is turned off; consequently the current consumption is'of'course far lower than with previous devices of'this kin heater proper formed in this way is,

shaped dish 2 1] swing an inner lining (l of asbestos or the like, the said dish after having been filled with the insulating compound be ing placed int} Le hollow space formed by the customary flan ge mass, which is still in a 'lastic state, may

the bottom of ti 1e vessel, If now by turning "on the electric current the heater-is brought to incandescenca or at leaststrongly heated,

the insulating mass 0 becomes hardened in give the best results due to the V vessel theheat developed by tljl' heater is evenly distributed over the entire reference being had to the crushed ordj ing to the invention, embedded in a plate at the underside of the vessel to behuated so that the insulating to the lower edge-0f the said vessel! .over the the form imparted to. it by the bottom of the vessel and-will consequently each time when used always lie perfectly close against the bottom surface. of the vessel to be heated .without the employment of mechanical means. Owing to the special nature of the insulating compound above described, a heater having an alm'ost unlimited life is obtained even when subjected to the most severe use conceivable.

In order to adapt-v porcelain, china, or

similar utensils or vessels for use with the above heater, the vessels are according to Fig. 3 appropriately provided on their lower edge with a depending annular flange fhavthe use of a heater which merely heats'the bottom of the'vessel, the said vessels are-pro videdwith a conductive coating on the outer side' by means of a process patentedby the v applicant, and the space formed by said dependin flange and intended to receive the heater 1n such vessels may be provided by taking a vessel h which has been finitially provided with a thin coating 71 and/soldering or welding a metal ring k of suitable height deposit 5; the line of connection is neatly plastered up and both the vessel and the ring and vessel and 70' are together provided with a thin conductive coating Z, which now connects .the ring is with the metal coating of the vessel and consequently with the vessel itself so as to make quite a uniform whole. If the heater is inserted into the ring it, which is of course provided with recesses g for the contacts Z) and heated, the heat developed is conveyed not only direct to the bottom of the vessel but also through the ring A: and the metal coating of the vessel to its side walls, thereby effecting the heating of such vessels with great speed and economy.

The contacts I) are kept out of contact with the metal ring A: by proper-insulation in order to avoid a short circuiting of the electrical circuit.

Claim:

An electrical cooking apparatus of the character described, comprising a cooking utensil and an electric heating device provided respectively with heat transmitting surfaces, said cooking utensil being provided with a conductive outer covering, a recessed metal ring at the bottom of said utensil uniformly connected thereto by said conductive covering, and wires insulated from said ring assing through the recesses insaidring, reslstance wires embedded in an insulating mass at the bottom of said utensil, said wires being adapted to conductively connect the resistance wires to a source of energy, substantially as described. In testimony whereof I aflix my signature in the presence of .two witnesses LEO HELLER. Witnesses: Arom Freeman,

RUDOLF ScHowIcK. 

